In the field of off-highway trucks used in mining operations, for example, it is desirable that an accurate record be kept of the quantity of material removed from the mining site. This information can be used to calculate mine and truck productivity as well as aid in forecasting profitability and work schedules.
Other systems, as disclosed in U.S. Pat. No. 4,635,739 issued to D. Foley et al. on Jan. 3, 1987, have shown that strut pressure can be an accurate indicator of payload. The apparatus disclosed therein includes an electronic control which monitors each of the strut pressures, compensates for various inaccuracies introduced by load distribution and vehicle attitude, and correlates this information into actual payload. This payload information allows the truck to be operated efficiently near its maximum capacity without promoting undue vehicle wear. An overloaded vehicle hastens tire and frame damage.
Improper payload distribution also promotes vehicle wear. Strut, frame, and tire damage can occur easily if the payload is distributed unevenly. The payload monitor accurately calculates payload with an unsymmetrical distribution, but does not fully protect the vehicle frame and suspension from overloads. Merely determining the actual payload to prevent overloading is not sufficient to fully protect the vehicle, since uneven distribution causes overloads on portions of the vehicle.
Heretofore, there have been no devices for displaying the payload distribution of a dump truck to an operator. Some prior art shows weight distribution on each axle for multi-axled vehicles. However, this information is inadequate for very large off-highway dump trucks. Many trucks of this type use electric motors to drive each side of an axle. If the load on one side is much larger than the load on the opposing side, then one electric motor works much harder than the other. The torque output necessary to move an excessive load can easily overdrive an electric motor. Repair and replacement of such motors is extremely expensive.
Truck operators often park incorrectly during loading. Level ground should be sought to prevent one strut from receiving much more load than another. For instance, parking with a rear tire on a small hill or grade can cause that portion of the truck to accept as much as 90 percent of the load, while an adjacent portion may exhibit a negative load. The implications of such a loading configuration are obvious. Suspension and frame damage can easily occur during loading from an improper loading position, due to the extreme load on the suspension structure and the torsional forces propagating through the frame.
The present invention is directed to overcoming one or more of the problems as set forth above.